I make this as a quick lunch all the time. Kids love it and it is easy for them to make too. You can add additional toppings as desired; try some slices of onion.
Place the pita bread on a baking tray and spread with the tomato paste. Sprinkle over the cheddar cheese. Slice the ham into thin strips and distribute it over the cheese. Evenly place the olives on top.
Grill 5-10 minutes or until the cheese has melted and is starting to brown.